As for the nervous differentiation induction medicine which is offered by this invention, at least a kind of cell being the nervous differentiation induction medicine which at least contains a kind of can differentiate induce in the nerve cell and peptide, as the aforementioned peptide: The peptide which in each case belongs to the SOCS protein includes the amino acid arrangement to which part alteration is administered to BC- box origin amino acid arrangement or the said arrangement which consists of the amino acid residue which 10 where it is selected from the amino acid arrangement which forms the BC- box of a kind of protein continue at least is synthesized artificially It contains.本発明によって提供される神経分化誘導剤は、少なくとも一種の細胞を神経細胞に分化誘導し得る少なくとも一種のペプチドを含有する神経分化誘導剤であって、前記ペプチドとして:SOCS系タンパク質に属する何れか一種のタンパク質のBC-ボックスを構成するアミノ酸配列から選択される少なくとも10個の連続するアミノ酸残基から成るBC-ボックス由来アミノ酸配列又は該配列に部分的な改変が施されたアミノ酸配列を含む人為的に合成されたペプチド;を含有する。
